1. Field of the Invention
The present invention relates to a cylinder intake air amount calculating apparatus for calculating a cylinder intake air amount which is an amount of fresh air sucked in a cylinder of an internal combustion engine.
2. Description of the Related Art
Japanese patent laid-open No. H2-157452 (JP'452) discloses a fuel injection amount control apparatus which calculates a predicted value of the cylinder intake air amount of an internal combustion engine, and calculates a fuel injection amount based on the calculated predicted value. According to this apparatus, a preceding predicted value of the cylinder intake air amount and the detected intake air flow rate are applied to a physical model equation which is set based on the mass-conservation law of the intake air, to calculate a present predicted value of the cylinder intake air amount, and the fuel injection amount is calculated based on the present predicted value. By using the predicted value, accuracy of the air-fuel ratio control is improved in the transient operating condition of the engine.
The predicted value naturally includes a prediction error. Therefore, it is desired that the method of JP'452 in which the predicted value of the cylinder intake air amount is calculated using the preceding predicted value, may be further improved in calculation accuracy of the predicted value.